At the core of every successful Retro-Commissioning (RCx) project is an effective collaboration between the commissioning agent and the building's operating staff to identify and implement energy conservation measures. This session will provide guidance to commissioning agents and building operations teams about how to work together throughout the Retro-Commissioning (RCx) process to maximize the benefits of RCx. We will present examples from both the commissioning agent building operations perspectives of how previous project collaborations have been structured, including the development of training materials, to attain significant and sustained benefits beyond energy savings.